Serotonin (5-HT) is a monoamine neurotransmitter and exerts various physiological actions via the 5-HT receptor. The 5-HT receptor is classified into seven families of from 5-HT1 to 5-HT7. Particularly, the 5-HT2 receptor is known to have three subtypes, 5-HT2A, 5-HT2B and 5-HT2C (Non-patent Reference 1).
The irritable bowel syndrome (IBS) is a disease in which an abdominal pain or an abdominal unpleasantness continues for a prolonged period of time. Based on its symptoms, IBS is classified into a diarrhea type, a constipation type and a mixed type of diarrhea and constipation. In each case, it has been pointed out that there is a causal relation between the morbid state and the amount of 5-HT in blood. For example, there is a reference which points out that increase of blood 5-HT concentration after meal occurs in diarrhea type IBS patients and this is deeply concerned in the morbid state (Non-patent Reference 2).
Currently, though it is at the clinical trial in Japan, a 5-HT receptor antagonist or a 5-HT receptor agonist is used in Europe and America as an agent for treating IBS. As an agent for treating diarrhea type, alosetron (5-HT3 receptor antagonist) is used in the clinical field, but side effects such as ischemic colitis, constipation and the like have  been reported. In addition, as an agent for treating constipation type, tegaserod (5-HT4 receptor agonist) is used in the clinical field in Europe and America, but side effects have also been reported (Non-patent References 3 and 4).
In recent years, pharmacological studies on other 5-HT receptor subtypes have also been carried out (Non-patent Reference 5). Regarding the 5-HT2B receptor and 5-HT7 receptor, there are reports which pointed out roles of said receptors in digestive tracts. For example, there are reports stating that the 5-HT2B receptor localizes in human ileum longitudinal muscle and a 5-HT2B receptor antagonistic compound suppresses contraction by 5-HT (Non-patent Reference 6), and that the 5-HT2B receptor localizing in human colon is concerned in the 5-HT-induced contraction at the time of electric stimulation and a 5-HT2B receptor antagonistic compound suppresses it (Non-patent Reference 7).
In addition, there are reports stating that the 5-HT7 receptor localizes in guinea pig small intestines (Non-patent Reference 8) and rat small intestines (Non-patent Reference 9) and is concerned in the peristalsis of guinea pig ileum (Non-patent Reference 10). Also, in the Patent Reference 1 which was applied by the present applicant and laid open to public after priority date of the instant application, it is reported that a selective 5-HT2B and 5-HT7 receptor dual antagonist is useful in treating IBS. Based on the above, it is expected that a compound having the antagonistic activity for 5-HT2B and 5-HT7 receptors is useful as an IBS treating agent.
In addition, since there are reports stating that a selective 5-HT2B and 5-HT7 receptor dual antagonist is useful in preventing migraine (Patent References 2 and 3), it is expected that a compound having the antagonistic activity for 5-HT2B and 5-HT7 receptors is also useful as an agent for preventing migraine.
As the compound having the antagonistic activity for 5-HT2B and 5-HT7 receptors, there are reports of the following Patent References 1 to 4. 
It has been reported that a fluorene derivative represented by the following formula (A) has the antagonistic activity for 5-HT2B and 5-HT7 receptors and is useful in preventing migraine (Patent References 2 and 3) and in treating IBS (Patent Reference 1).
(See said official gazettes for symbols in the formula.)
In addition, as the amide derivatives having a nitrogen-containing bicyclic hetero ring (e.g., indole or the like), the following reports exist.
In the Patent Reference 4, it is reported that an indolylguanidine derivative represented by the following formula (B) has the sodium/proton antiporter system inhibitory action and is effective in treating and preventing high blood pressure, heart muscle ischemia, reperfusion injury and the like. However, there are no descriptions on its 5-HT2B and 5-HT7 receptor antagonistic activities and its efficacy for IBS.
(See said official gazette for symbols in the formula.)
In the Patent Reference 5, it is reported that a benzo-condensed heterocyclic compound represented by the following formula (C) has the sodium/proton exchange inhibitory action and is useful as an agent for treating heart diseases such as arrhythmia and the like. However, there are no descriptions on its 5-HT2B and 5-HT7 receptor antagonistic activities and its efficacy for IBS. 
(See said official gazette for symbols in the formula.)
In the Patent Reference 6, it is reported that an indole derivative represented by the following formula (D) has the cannabinoid receptor-regulating action and is useful as an agent for preventing or treating or an agent for diagnosing cerebrovascular disorders, etc. However, there are no descriptions on its 5-HT2B and 5-HT7 receptor antagonistic activities and its efficacy for IBS.
(See said official gazette for symbols in the formula.)
In the Patent Reference 7, it is reported that a benzimidazole derivative represented by the following formula (E) is useful for renal diseases. However, there are no descriptions on its 5-HT2B and 5-HT7 receptor antagonistic activities and its efficacy for IBS. 
(See said official gazette for symbols in the formula.)
In Non-patent Reference 11, a solid phase synthesis method of a benzimidazole derivative represented by the following formula (F) is reported. However, there are no descriptions on its 5-HT2B and 5-HT7 receptor antagonistic activities and its efficacy for IBS.
(See said official gazette for symbols in the formula.)
Also, 1-benzyl-N-[2-(dimethylamino)ethyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 312604-61-8), 1-benzyl-5-[(4-ethylpiperazin-1-yl)carbonyl]-2,3-dimethyl-1H-indole (CAS Registry No. 515828-64-5), 1-benzyl-5-[(4-benzylpiperazin-1-yl)carbonyl]-2,3-dimethyl-1H-indole (CAS Registry No. 338984-26-2), and 5-[(4-benzoylpiperazin-1-yl)carbonyl]-1-benzyl-2,3-dimethyl-1H-indole (CAS Registry No. 309727-87-5), N-(1-benzylpiperidin-4-yl)-1-(4-methoxybenzyl)-2-oxo-2,3-dihydro-1H-benzimidazole-5-carboxamide (CAS Registry No. 846563-08-4) and N-(1-benzylpiperidin-4-yl)-1-(4-fluorobenzyl)-2-oxo-2,3-dihydro-1H-benzimidazole-5-carboxamide (CAS Registry No. 846563-01-7) have been reported as catalog  compounds. However, there are no reports on the 5-HT2B and 5-HT7 receptor antagonistic activities of these compounds and their efficacy for IBS.
In addition, in a catalog “Aurora Screening Library” (STN data base, date of publication by CHEMCAT, May 10, 2006), published by Aurora fine Chemicals after the priority date of this application, N-(1-benzylpiperidin-4-yl)-1-(4-fluorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895121-54-7), 1-benzyl-N-(1-benzylpiperidin-4-yl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895117-17-6), N-(1-benzylpiperidin-4-yl)-1-(4-chlorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895097-35-5), 1-(4-fluorobenzyl)-5-{[4-(4-fluorophenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole (CAS Registry No. 895122-22-2), 1-(4-fluorobenzyl)-2,3-dimethyl-5-[(4-pyridin-2-ylpiperazin-1-yl)carbonyl]-1H-indole (CAS Registry No. 895122-18-6), 1-(4-fluorobenzyl)-2,3-dimethyl-5-{[4-(4-nitrophenyl)piperazin-1-yl]carbonyl}-1H-indole (CAS Registry No. 895122-14-2), 5-{[4-(4-chlorophenyl)piperazin-1-yl]carbonyl}-1-(4-fluorobenzyl)-2,3-dimethyl-1H-indole (CAS Registry No. 895122-06-2), 1-benzyl-5-{[4-(2-fluorophenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole (CAS Registry No. 895119-58-1), 1-benzyl-2,3-dimethyl-5-[(4-pyrimidin-2-ylpiperazin-1-yl)carbonyl]-1H-indole (CAS Registry No. 895119-53-6), 1-benzyl-5-{[4-(4-fluorophenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole (CAS Registry No. 895119-48-9), 1-benzyl-2,3-dimethyl-5-[(4-pyridin-2-ylpiperazin-1-yl)carbonyl]-1H-indole (CAS Registry No. 895119-38-7), 1-benzyl-5-{[4-(2,5-dimethylphenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole (CAS Registry No. 895119-23-0), 1-benzyl-5-{[4-(2,3-dimethylphenyl)piperazin-1-yl]carbonyl}2,3-dimethyl-1H-indole (CAS Registry No. CAS 895119-18-3), 1-benzyl-2,3-dimethyl-5-[(4-phenylpiperazin-1-yl)carbonyl]-1H-indole (CAS Registry No. 895119-08-1), 2,3-dimethyl-1-(3-methylbenzyl)-5-[(4-pyridin-2-ylpiperazin-1-yl)carbonyl]-1H-indole (CAS Registry No. 895100-05-7), 1-(4-chlorobenzyl)-5-{[4-(2-fluorophenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole  (CAS Registry No. 895099-04-4), 1-(chlorobenzyl)-2,3-dimethyl-5-[(4-pyrimidin-2-ylpiperazin-1-yl)carbonyl]-1H-indole (CAS Registry No. 895098-99-4), 1-(chlorobenzyl)-5-{[4-(2,5-dimethylphenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole (CAS Registry No. 895098-94-9), 1-(chlorobenzyl)-5-{[4-(2,3-dimethylphenyl)piperazin-1-yl]carbonyl}-2,3-dimethyl-1H-indole (CAS Registry No. 895098-89-2), 1-(4-fluorobenzyl)-2,3-dimethyl-N-(3-pyrrolidin-1-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895121-82-1), 1-(4-fluorobenzyl)-2,3-dimethyl-N-(2-morpholin-4-ylethyl)-1H-indole-5-carboxamide (CAS Registry No. 895121-66-1), 1-(4-fluorobenzyl)-2,3-dimethyl-N-(3-morpholin-4-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895121-14-9), 1-benzyl-N-[4-(dimethylamino)benzyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895121-14-9), 1-benzyl-2,3-dimethyl-N-[2-(4-methylpiperazin-1-yl)ethyl]-1H-indole-5-carboxamide (CAS Registry No. 895118-43-1), 1-benzyl-N-[3-(4-benzylpiperazin-1-yl)propyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895118-33-9), 1-benzyl-N-[3-(4-benzylpiperazin-1-yl)propyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895118-28-2), 1-benzyl-N-{3-[4-(2-fluorophenyl)piperazin-1-yl]propyl}-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895118-18-0), 1-benzyl-2,3-dimethyl-N-[2-(2-methylpiperidin-1-yl)ethyl]-1H-indole-5-carboxamide (CAS Registry No. 895118-13-5), 1-benzyl-2,3-dimethyl-N-(3-pyrrolidin-1-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895118-08-8), 1-benzyl-2,3-dimethyl-N-[3-(2-methylpiperidin-1-yl)propyl]-1H-indole-5-carboxamide (CAS Registry No. 895118-03-3), N-(3-azepin-1-ylpropyl)-1-benzyl-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895117-98-3), 1-benzyl-N-[3-(2-ethylpiperidin-1-yl)propyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895117-98-3), 1-benzyl-2,3-dimethyl-N-(3-piperidin-1-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895117-88-1), 1-benzyl-2,3-dimethyl-N-[3-(4-methylpiperazin-1-yl)propyl]-1H-indole-5-carboxamide (CAS Registry No. 895117-83-6), 1-benzyl-2,3-dimethyl-N-(2-morpholin-4-ylethyl)-1H-indole-5-carboxamide (CAS Registry No. 895117-59-6), 1-benzyl-2,3-dimethyl-N-(3-morpholin-4-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895116-57-1), 2,3-dimethyl-1-(3-methylbenzyl)-N-(2-morpholin-4-ylethyl)-1H-indole-5-carboxamide (CAS Registry No. 895099-84-0), 1-(4-chlorobenzyl)-N-[4-(dimethylamino)benzyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895099-24-8), 1-(4-chlorobenzyl)-2,3-dimethyl-N-[3-(4-propylpiperazin-1-yl)propyl]-1H-indole-5-carboxamide (CAS Registry No. 895098-39-2), 1-(4-chlorobenzyl)-2,3-dimethyl-N-[2-(2-methylpiperidin-1-yl)ethyl]-1H-indolyl-5-carboxamide (CAS Registry No. 895098-30-3), 1-(4-chlorobenzyl)-N-3-(4-ethylpiperazin-1-yl)propyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895098-26-7), 1-(4-chlorobenzyl)-2,3-dimethyl-N-(2-pyrrolidin-1-ylethyl)-H-indole-5-carboxamide (CAS Registry No. 895098-13-2), N-(2-azepan-1-ylethyl)-1-(4-chlorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895098-08-5), 1-(4-chlorobenzyl)-2,3-dimethyl-N-(3-pyrrolidin-1-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895098-04-1), 1-(4-chlorobenzyl)-2,3-dimethyl-N-[3-(2-methylpiperidin-1-yl)propyl]-1H-indole-5-carboxamide (CAS Registry No. 895098-00-7), N-(3-azepan-1-ylpropyl)-1-(4-chlorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895097-96-8), 1-(4-chlorobenzyl)-2,3-dimethyl-N-(3-piperidin-1-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895097-88-8), 1-(4-chlorobenzyl)-2,3-dimethyl-N-[3-(4-methylpiperazin-1-yl)propyl]-H-indole-5-carboxamide (CAS Registry No. 895097-84-4), 1-(4-chlorobenzyl)-2,3-dimethyl-N-(2-morpholin-4-ylethyl)-1H-indole-5-carboxamide (CAS Registry No. 895097-63-9), 1-(4-chlorobenzyl)-2,3-dimethyl-N-(3-morpholin-4-ylpropyl)-1H-indole-5-carboxamide (CAS Registry No. 895096-80-7), N-[2-(dimethylamino)ethyl]-1-(4-fluorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895120-70-4), N-{3-[benzyl(ethyl)amino]propyl}-1-(4-chlorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895098-21-2), N-{3-[butyl(ethyl)amino]propyl}-1-(4-chlorobenzyl)-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895098-17-6), 1-(4-chlorobenzyl)-N-{3-[ethyl(3-methylphenyl)amino]propyl}-2,3-dimethyl-1H-indole-5-carboxamide (895097-92-4),  and 1-(4-chlorobenzyl)-N-2-(dimethylamino)ethyl]-2,3-dimethyl-1H-indole-5-carboxamide (CAS Registry No. 895096-32-9), N-[(1-ethylpyrrolidin-2-yl)methyl]-1-(4-methoxybenzyl)-2-oxo-2,3-dihydro-1H-benzimidazole-5-carboxamide (CAS Registry No. 878688-87-0) and N-(1-benzylpiperidin-4-yl)-2-oxo-1-(2-phenylethyl)-2,3-dihydro-1H-benzimidazole-5-carboxamide (CAS Registry No. 846563-24-4) have been reported. However, there are no reports on the 5-HT2B and 5-HT7 receptor antagonistic activities of these compounds and their efficacy for IBS.    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